First, make sure you are using an iPhone™ 5, 4S, 4, 3GS or 3G. First generation iPhones and the iPod® touch do not have the necessary GPS chipset to acquire an accurate signal.
Ensure your iPhone™ has a clear view of the sky. GPS requires a direct ‘line-of-site’ to communicate with satellites. Your iPhone™ 5, 4S, 4, 3GS or 3G must have a clear view of the sky to locate at least three satellites in order to give accurate position information. If you are located indoors, or in a wooded area or urban canyon (surrounded by buildings), you may be unable to acquire an accurate signal.
If you can not acquire a signal within two minutes, try using “Reset Location Warnings” under the iPhone’s settings in General >> Reset.
If you are having trouble maintaining a GPS signal and you are flying or traveling at speeds above 150 mph/240 km/h, you may wish to switch off the Accuracy Filter off under Settings > Global Settings.
If you are still having trouble acquiring a GPS signal, try powering your iPhone™ off, then turn it back on and launch MotionX-GPS. If prompted, allow MotionX-GPS to use Location Services by selecting “Ok”.
The iPhone™ 5, 4S, 4, 3GS and 3G use cell towers to speed up acquisition of the GPS signal. While it typically takes between 1-5 minutes to locate a signal, it can take up to 15 minutes in areas where cellular coverage is not available.
The iPhone™ 5, 4S, 4, 3GS and 3G also has a service by Skyhook which uses WiFi to help speed up the GPS signal acquisition. If the location data for the WiFi signal you’re picking up is incorrect in Skyhook’s database, it could be interfering rather than helping to speed up the GPS signal search.
Skyhook has a form you can fill out to correct the location of the WiFi access point. Here is a link to the form. You will need your actual Latitude and Longitude, the MAC address of the WiFi access point and your email address to submit a correction. The form has a link to show you where to find the MAC address if you don’t know where to look.